Method of finishing piston-ring grooves



Nov 27 1923, 1,4?5fi62 G. A. TAYLOR METHOD OF FINISHING PISTON RINGGROOVES Filed June 21.. 1922 INVEN+UVZ consists that all the grooves ofPatented Nov. 27, 19230 GEQBG-E A. TAYLOR, 01E EOS' I'ON, SACHUSETUES.

METHQJD 0E FINISHING- PISEQN-MNG GEQQVES.

Application filed June all, 1922'. denial the. aroma To all whom it mayBe it .lniown that ll, Gannon A. 'la. me; a citizen of the UnitedStates, residing at Boston, county of Suolk, State of -Massachusetts,have invented a certain new and useful Improvement in Methodsol.Finishing Piston-Ring Grooves, of which the following is aspecification, reference being had therein to the accompanying drawin.'My invention relates to the manuacture of pistons for internalcombustion engines and like articles which are provided with annularslotsin which the piston rings are placed. It is important that the,parallel walls of these slots shall be true, ot the correct distanceapart, and as highly. finished as possible, so that a gas tight seatshall be made between the proximate faces of the ring and groove. Mypresent invention, therefore, has for its object a novel method ofenlarging, truing and finishing ring slots in pistons and like articles.The/method" primarily in forcing or rolling.

through the slots a sharp-edged disk the width of which is slightlygreater than the original width of the slot so that the edges of thedisk shear or scrape oil from the side walls of the slots a minute layerof metal, leaving the surface of the metal scraped or highly polishedand the groove of uniform lln practice ll find.-

diameter throughout.

a piston can be ished at the same time by the use of a plurality ofaxially movable disks mounted on an arbor. j

in practicing my novel method, I employ disks with sharp edges having ashear-' ing' action so that they scrape or otherwise remove from theparallel surfaces of the groove a minute layer of metal. ll, find inactual practice that this results'in the production of a highly finishedsurface and renders the groove true and accurate in width throughout itslength, thereby producing a surface or surfaces against which thecorresponding surface or surfaces of the piston ring will seat and makeagas-tight oint.

pointed out and clearly defined in the claim at the close of this secification In the drawings, ig. 1 is a view of a ma.-

lhe invention will be fully understood chine for practising the novelmethod cinbodying my invention.

Fig. 2 is a section taken on line 2-2 of Fire 1. v

,Fig. 3 is a detail view showin the construction of onev oi the rollerdiss used in the finishing operation. Fig. at is a view on an-enlargedscale of the grooved. portion of the piston showing the sheet on thepiston'ot the finishing method described herein.

--Reterring now to the drawings, atll is shown a piston having threegrooves, a, b and 0. These grooves are formed by ordinary methods andmachined. Thereafter, the piston is supported on an arbor LIB-which canbe rotated by a pulley l3. lln a suit the arbor. Each of the disks, asshown in Figure 3, has flat end faces at and e, and a smooth cylindricalperipheral surface f makingsharp peripheral edges 9 and ii... The

thickness of the disk is slightly greater than the width of the groovein which it is to be used. .lln practice ll find that it is well to makethe disk .004.- or .005 of an inch thicker than the width of the grooveso that the shaving or scraping which will be removed will be from .002to 002% of an inch in thickn.

Illo finish the walls of the grooves a, l), and o in the piston, disksare moved upto the piston on the slide 20 on which the station ary arbor17 is mounted. The piston is then caused to revolve slowly and the slide20 fed toward the axis of the piston so that the disks gradually enterthe grooves and as the piston revolves the disks are rotated, removingprogressively a minute portion 73 of the surface, shown in F igure 4,and leaving the walls in a highly polished condition and of uniformwidth. The shavings or scrapings are forced into the bottom of thegroove and are so minute that they do not interfere with the operationof the disks.

While my invention in its broadest form contemplates the use of a singledisk to finish the flat surface of a piston ring groove, in practice Iemploy as many disks as there are grooves, performing the operation onall of the grooves simultaneously in the manner shown. This is perfectlypracticable, since the disks, if mounted to be slightly movable axiallyof the arbor on which they are mounted, adjust themselves to anyvariations in the relative-position of the grooves.

The method embodying my invention not only produces a better piston thanhas heretofore been produced, but does so without subjecting it to anyundue strains, as is the case where an attempt is made to compress themetal of the walls otthe grooves.

In the ioregoing description of the disk employed, I have used theexpression a sharp edge to designate the construction of the toolemployed. By the phrase sharp edge, I intend to connote any edge whichhas the effect of cutting, i'. e. removing metal from the wall indistinction to one which by reason of its shape or character isincapable of doing so.

What I claim is:

The method of enlarging, truing and finishing the ring slot in a pistonor the like article, which consists in passing through the slot adisk-shaped roller having a sharp edge,

the width of the roller being slightly greater than the original widthof the slots.

In testimony whereof I aiiix my si GEORGE A. TA

ature.

